Studies On The Polyurea Material For Concrete In Marine

Numbers of marine structures are constructed with the exploitation of the marineresources and utilize of the marine spaces.However,the marine structure corrosionoccurs gravely due to envirmental factors,which diminish the safety and durability ofthe marine concrete structure fearfully.Polyurea as the protective coating of concreteare widely concerned.In this paper,the properties of polyurea as the protective coating was studied,whichincluded weathering test, chloridion permeability,abrasion resistance,impermeabilityand frost resistance.Finally,the attention of polyurea application was analysised.Themain conclusions are as follows:Firstly, the weathering test of polyurea was inserched by artificial weatheringtest.The tensile strength of polyurea of curing age7days was22.59MPa,and theelongation at break was460.43%.After aging3000hours,the tensile strengthdecreased by3.20%,and the elongation at break decreased by1.18%.By RCP,thecharges of passed of concrete and coated concrete was1693.8C and2.59C.After aging,the charges of coated concrete was2.75C.The ATR-FTIR result indicate that themolecular chains of coating surface are broken in both soft segment and hardsegment,but there has no change interior-molecular structure of coating.Secondly, wear-resistant performance of polyurea was studied by high silt-ladenflow.The result shows that the thickness loss of polyurea is only0.14%of that inexpoy, and the mass loss rate is only0.18%of that in C50concrete.The adhesion ofthe polyurea and concrete is3.56MPa and3.58MPa.The wear-resistant performanceof polyurea is much more better than expoy coating and C50concrete.Thirdly,the experimental results from anti-permeability of polyurea show that thepolyurea whose thickness is1.0mm could withstand0.3MPa pressure,the thickness1.5mm polyurea could withstand0.5MPa,the thickness2.0mm polyurea couldwithstand0.7MPa pressurea.The polyurea could be used as the inner waterproofing layer of concrete structure.Then,the freeze-thawing cycle resistance of coated concrete was studied.Researchresults showed that polyurea coated concrete has better frost resistance. The relativedynamic elastic modulus of uncoated concrete decreased by40.31%and the mass lossdecreased by95.32%after300cycles.The relative dynamic elastic modulus of1.0mmpolyurea coated concrete after400cycles began to dropped and when750cycles, therelative dynamic elastic modulus reduced by99.74%，and the mass loss changed0.11%. After750times freeze-thawing cycles,2.0mm polyurea coated concrete wasintact, and the quality and the relative dynamic elastic modulus remained unchanged.And then, the chloridion penetration of different thickness polyurea coated concretewas reserched in freeze-thawing cycle by titration. The results showed that concreteprotective coatings could improve the resistance to chloride penetration of concrete.And the resistance value increased with the thickness of coat.Through the above experiments and academic analysis, this paper provides ascientific and reasonable test data for Qingdao bay bridge, establishes foundation forthe application of SPUA technology in the protection of marine concrete structure,also supplies reference for the congener marine engineering construction.